UPSTREAM: rcu: Refactor code a bit in rcu_nocb_do_flush_bypass()

This consolidates the code a bit and makes it cleaner. Functionally it
is the same.

Bug: 258241771
Bug: 222463781
Test: CQ
Reported-by: Paul E. McKenney <paulmck@kernel.org>
Signed-off-by: Joel Fernandes (Google) <joel@joelfernandes.org>
Reviewed-by: Frederic Weisbecker <frederic@kernel.org>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>

(cherry picked from commit 3d222a0c)
Change-Id: I8422c7138edd6a476fc46374beefdf46dd76b8b0
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/third_party/kernel/+/4318047


Tested-by: Joel Fernandes <joelaf@google.com>
Reviewed-by: Sean Paul <sean@poorly.run>
Reviewed-by: Vineeth Pillai <vineethrp@google.com>
Commit-Queue: Joel Fernandes <joelaf@google.com>
(cherry picked from commit 58cb433d445d2416ba26645e8df63d86afa15f8c)
[Cherry picked from chromeos-5.15 tree. Minor tweaks to commit message
to match Android style]
Signed-off-by: Qais Yousef <qyousef@google.com>